The present invention relates in general to the utilization and control of various accessories which are associated with a particular vehicle or engine. More specifically, the present invention relates to the distribution of engine power (horsepower) between various engine or vehicle functions and accessories in order to provide additional power to one function and less power to another function. Similarly, in accordance with the present invention one function may be to engage or activate and another function may be to disengage or deactivate in order to divert the necessary horsepower to the function being energized or activated.
Generally speaking any engine, whether a motor vehicle engine, an engine used for farm machinery or some other type of industrial engine, has certain limits as to the available power output or horsepower available at the flywheel. The more accessories or other functions which are to be driven by the engines power output, the greater the overall horsepower drain on the engine. In certain situations the total horsepower drain or load on the engine is so close to the maximum power which is available that it is not possible to provide increased boost power. As a consequence, there may be occasions when some additional task or function by means of a related accessory is desired to be performed, but the necessary horsepower is simply not available without detracting or draining power from some other engine function. A result of activating or energizing this additional task or function could be unsatisfactory engine performance, such as a diversion of engine horsepower and a corresponding reduction in engine or vehicle speed. For example, an automobile has greater acceleration when its air conditioner is turned off, because the power drain caused by the air conditioner is available for the engine to use for acceleration.
Another practical example of the aforementioned situation can be provided by considering a farm combine (with an unloader) which is moving at a preferred and desired speed. The farmer then wishes to operate the unloader. Without the concepts, functions and structure of the present invention, the energizing or activation of the unloader would cause a power drain on the engine which in turn would cause a speed reduction. As a consequence of the speed reduction, the combine is no longer traveling at the preferred or desired speed and this must be viewed as a disadvantage or shortcoming as to the overall operation of the combine.
According to the present invention this problem is solved by sensing the activation or engagement of the unloader and then turning off some other power-absorbing accessory, such as the engine cooling fan. In this way the total power demand is not materially affected, there has simply been a shifting, diverting or redistribution of the available power. As a consequence, the preferred and desired combine speed can be generally maintained.
Since the deactivation of the cooling fan might, depending upon several factors, cause the engine (coolant system) temperature to creep toward an unacceptable level, the present invention includes appropriate sensors to protect the engine. If the temperature sensor shows that the cooling system is at or above a particular threshold level, the cooling fan is either not disengaged in the beginning or is reengaged whenever the threshold temperature is reached so as to protect the engine.
A second level logic decision could be made, according to the present invention, if it is not possible to disengage the cooling fan due to the engine temperature. It is possible to sense the condition or status of some other power-absorbing accessory which could then be disengaged or deactivated in lieu of the cooling fan. While the power drain for this secondary accessory might be less than the power drain or power consumption required by the cooling fan, disengaging this secondary accessory would still provide some additional horsepower back to the engine and thus while the unloader was operating the slowing effect on the engine and ultimately vehicle speed would be lessened by the supplemental horsepower from the secondary accessory.
Over the years a few attempts have been made by others to engage and disengage engine accessories according to certain performance strategies. A representative sampling of these earlier efforts is believed to be provide by the following patent references:
______________________________________ Patent No. Patentee Issue Date ______________________________________ 2,706,468 Wilcox Apr. 19, 1955 2,720,087 Groene Oct. 11, 1955 2,822,790 Bartholome Feb. 11, 1958 3,096,662 McRae Jul. 9, 1963 3,596,524 Cook Aug. 3, 1971 4,425,766 Claypole Jan. 17, 1984 4,651,922 Noba Mar. 24, 1987 4,881,494 Ishigami Nov. 21, 1989 4,941,437 Suzuki, et al. Jul. 17, 1990 5,094,332 Wall Mar. 10, 1992 5,117,898 Light et al. Jun. 2, 1992 5,133,302 Yamada et al. Jul. 28, 1992 ______________________________________
Although a variety of concepts and structures are disclosed by the foregoing listed patents none provide the specifics of the present invention. For example, Wall ('332) discloses a control system for engaging and disengaging a clutch connected between an engine and an accessory, such as an air conditioning compressor of a vehicle. The system includes a microprocessor 12 for controlling both the initial engagement and subsequent operation of the clutch 11 in response to various sensed conditions, such as the level of engine vacuum and thus engine load. Microprocessor 12 may delay engagement of the clutch 11 until the load on the engine is reduced, thus preventing stalling of the engine. However, this reference fails to specifically disclose a control system which disengages a power-absorbing accessory from the engine in response to the actuation of a second power-absorbing accessory connected to the engine.
As another example of the deficiencies of these earlier efforts, McRae ('662) discloses an engine accessory drive which functions at certain high speeds of the engine to disengage the clutch to reduce the speed of the cooling fan and power steering pump while allowing the water pump to run at higher speeds. While this reference seems to recognize that the extra power required to run the water pump at engine speed is more than offset by the lower fan speed, it fails to disclose or suggest disengaging or unloading the fan or power steering pump upon the actuation of the other accessory.